Heater for oil pans of internal combustion engines



Oct. 19, 1965 w. A. STEENBERGEN 3,213,263

HEATER FOR OIL FANS OF INTERNAL COMBUSTION ENGINES Filed Nov. 12, 1963 2 Sheets-Sheet 1 ill INVENTOR. WILLIAM A. STu/va sac-25w ATTYS.

Oct. 19, 1965 w. A. STEENBERGEN 3,213,263

HEATER FOR OIL FANS OF INTERNAL COMBUSTION ENGINES Filed Nov. 12, 1963 2 Sheets-Sheet 2 INVENTOR.

WILLIAM A. STEENBERGEN ATTY6.

United States Patent 3,213,263 HEATER FOR OIL PANS OF INTERNAL COMBUSTION ENGINES William A. Steenhergen, Spokane, Wash., assignor to Kim Hotstart Manufacturing Company, Inc., Spokane,

Wash, a corporation of Washington Filed Nov. 12, 1963, Ser. No. 322,685 1 Claim. (Cl. 219-205) The present invention is concerned with a heater for the oil within the oil pan or sump of an internal combustion engine, such as those used on trucks, buses, automobiles, and other vehicles exposed to winter weather.

Internal combustion engines rely for lubrication upon a circulating oil system, which draws oil from a lower sump or oil pan located beneath the engine in most instances. While the engine maintains the oil supply in a warm condition while operating, the oil pan, in severe winter weather, acts as a radiator when the engine is inoperative and is not capable of maintaining the oil in a sufiicient warm condition for extended periods of time. It is necessary, under cold weather conditions, to use an extremely thin grade of oil, which does not have the wear qualities of those grades of oil having greater viscosity. Various heating systems are known for circulating warm water through the engine and radiator while the vehicle is at rest, but these again do not warm the storage oil in the lower pan, It is this oil that is intended to be maintained in a warm condition by use of the instant invention.

It is a first object of this invention to provide an oil heater for the pan of an internal combustion engine which can be readily mounted within the pan, and once mounted, can be fitted with replacement heating elements without the necessity of draining or emptying the pan, and without disturbing or contaminating the contents thereof.

'Another object of this invention is to provide such a heater which is simple in construction and which requires no periodic maintenance.

Another object of this invention is to provide a highly effective heat diffusion system, utilizing a continuous surface so that the temperature across the surface will be uniform, thereby insuring that oil in contact with any portion of the exposed surface will not become heated beyond its permissible limit.

These and further objects will be evident from a study of the following disclosure, taken in conjunction with the accompanying drawings which illustrate a preferred form of the invention. The preferred form of the invention illustrated in the drawings is exemplary, but is not intended to limit or restrict the scope of the invention, which is set out in the claim which follows.

In the drawings:

FIGURE 1 is a simplified elevation view of the lower portion of a typical engine, showing a pan equipped with the instant heater;

FIGURE 2 is an enlarged sectional view through the pan only, taken along line 2-2 in FIGURE 1 and illustrating the mounting of the heater;

FIGURE 3 is an enlarged end view of the outer end of the heater, with the protective cover removed;

FIGURE 4 is an enlarged end view of the inside of the cover alone as seen along line 44 in FIGURE 2;

'FIGURE 5 is an enlarged longitudinal sectional view taken through the entire unit; and

FIGURE 6 is an external view of the heating element alone.

In FIGURE 1 is shown the lower portion of a typical engine 10, provided with an oil pan 11 having side walls 12 and a lower wall r13. Oil flowing back to the pan 11 from the engine 10, after having been circulated through the engine, will be stored adjacent the lower wall 13, from which it is re-circulated by an oil pump (not shown). It

is this oil within the pan 11 which is subjected to extreme cold temperatures, while the engine is at rest.

In order to warm this oil, there is provided, according to the present invention, a heater unit which is shown in detail in FIGURES 2 through 6. The only modification necessary on a conventional oil pan is the provision of a circular boss 14 in the side wall 12 adjacent the lower or bottom wall 13. The boss 14 can be either an internal boss or an external boss, and is necessary in order to provide sufi'icient thickness for the threaded reception of the heating unit.

The unit used to heat the oil comprises several separable components, the first of which is a shell 15 that is cylindrical and hollow, the cross sectional configuration of shell 15 being continuous along its length. The inner end of the shell 15, which is denoted by the numeral 16, is closed, while the remaining end of the shell 15 is open. The interior of the shell 16 is formed by an axial bore of constant diameter. The open end of the shell 15 is provided with two sets of external threads, denoted as 17 and 18. The threads 17 and 18 are opposite in direction, and are tapered toward the narrow band 19 that separates them. The threads 17 are adapted to threadably engage within a suitably threaded aperture formed within the boss 14. Threads 17 are tapered so as to provide a tight fit in the pan 11, and so as to seal the interior of the pan 11 from the exterior atmosphere.

Slidably received Within the shell 15 is a heating element, comprising a thin walled tube 21 closed at its inner end 22. The tube 21 is open at its remaining end, and is filled with a conventional refractory insulating material 23 which encases a resistance type electrical heating element 24. The ends of the element 24 are connected to terminal screws 25 and 26 imbedded within the insulating material 23, as can best be seen in FIGURE 5. The terminal screws 25 and 26 are adapted to be electrically connected to the leads 27 and 28 respectively of a power cable 30 which is adapted to be connected to a suitable source of electrical energy, which might be located on the vehicle carrying the engine 10, or which more usually will be an external source.

The tube 21 is frietionally gripped by a recessed screw 20 extending inwardly at band 19, so that once in place, it is held from movement relative to the shell 15. The exterior diameter of the tube 21 is chosen so as to provide a close sliding fit within the interior bore: of the shell 15. The length of the tube 21 is approximately the interior length of the bore formed within the shell 15, so that close surface contact is maintained throughout the respective lengths of the shell 15 and tube 21.

Threadably mounted on the threaded portion 18 of the shell 15 is a collar 31, which includes a cylindrical shoulder 32. The collar 31 also engages the tapered threads 18, so as to provide a tight fit, and abuts the screw 20 as a limit to its movement relative to the shell 15. Interposed between the wall 12 of pan 11 and the collar 31 is a suitable annular gasket 36 to provide additional insurance against leakage of oil from the pan 11. The gasket 36 also serves to insulate the shell 15, where exposed to the exterior atmosphere, so as to minimize heat losses.

The unit is completed by a hollow cylindrical protective cap 33, which has an axial aperture within which is mounted a conventional gripping device 34 to engage the cable 30 and prevent it from being accidentally pulled from its connections with the terminal screws 25 and 26. The cover 33 protects the electrical connections and the open ends of the shell 15 and tube 21, and is held in place by two screws 35 that are threadably received within the cylindrical shoulder 32 of the collar 31.

The present device is designed particularly for the heating of conventional motor oils used to lubricate in- 1 3 ternal combustion engines. These oils cannot be exposed to a heating element with a concentration of power greater than 20 watts per square inch. In order to provide such a heater having minimum surface area, the maximum heat dissipation over a uniform area is required. This is achieved by utilizing a material in the shell that is corrosion resistant, and that which is capable of uniformly dissipating heat conducted through it. Many of the aluminum alloys available today will provide these necessary properties. The shell 15 is preferably made of stainless steel, which is not normally capable of uniformly spreading heat across its surface. The stainless steel shell 15 provides corrosion resistance, should Water or other liquids become entrapped between the shell 15 and the tube 21. The close surface contact provided by the sliding relationship between the tube 21 and the shell 15 provides efiicient heat transfer between the heating element and the conducting shell. In this manner, the shell 15 can be made with the minimum surface area necessary to maintain the heating power requirements without risking deterioration of the oil, taking also into account the conduction of heat through the pan wall 12 due to its intimate contact with the shell 15.

It has been found that the heater described above is most efficient in heating the quantities of oil required by an internal combustion engine, using a minimum power requirement to do so. The uniform surface of the shell 15 insures that oil contacting the shell 15 will not reach portions that are at a greater temperature than the oil can withstand safely. The unit is simple in construction, and can be readily mounted on pans of suflicient thickness to provide the necessary threaded fit. Once mounted, the interior element can be replaced without disturbing the pan or its contents by simply releasing the tube 21 and pulling it from the shell 15. This replacement is extremely simple and will require no unusual tools.

Many modifications might be made in the general design of the device, without deviating from the basic concept described, and for this reason only the following claims are intended to limit or restrict the invention.

Having thus described my invention, I claim:

In combination with an internal combustion engine oil pan having a side wall section provided with a boss of increased thickness adjacent the bottom wall of the pan, said boss having formed therethrough a tapered threaded bore increasing in diameter from the interior of the pan to its exterior; a heating unit comprising:

an elongated aluminum shell of cylindrical cross sectional configuration having at one end a tapered externally threaded portion complementary to the threaded bore formed through said boss of the pan, said shell having a hollow cylindrical interior of continuous cross sectional configuration open at said one end of said shell and closed across the remaining end of said shell,

a stainless steel tube slidably received within said shell having an exterior cross sectional configuration complementary in shape and size to the interior cross sectional configuration of said shell and slidably received therein for surface to surface contact therewith, said tube being open adjacent to said one end of said shell and being sealed across the walls thereof adjacent the remaining end of said shell;

an elongated electrical resistance heating element located within said tube and extending substantially throughout the length thereof, said element being positioned by rigid insulating material filling the remaining interior volume of said tube;

terminal means imbedded within said insulating material and protruding outwardly therefrom at the open end of said tube, said terminal means being electrically connected to the respective ends of said element;

cover means mounted on said shell enclosing the open end thereof, said cover means comprising:

a collar threadably engaged on the exterior of said shell adjacent the side wall of the pan;

an annular gasket interposed between the pan and said collar coaxially about said shell;

and a cylindrical cover removably seated on said collar and releasably secured thereto, said cover extending axially beyond said terminals;

and cable means extending through said cover means and electrically connected to said terminals, said cover having mounted therein means to frictionally grip said cable adapted to prevent its accidental displacement relative to said terminals, said cable means adapted to be connected to an external source of electrical energy.

References Cited by the Examiner UNITED STATES PATENTS 1,416,897 5/22 Simon 219-523 1,485,667 3/24 Coldwell 219-536 1,512,517 10/24 Astrom 219-208 1,618,761 2/27 Landsberger 219-205 X 1,692,741 11/28 Hurst 219-335 1,754,080 4/30 Briggs et al 219-205 1,770,642 7/30 Gelino 219-205 2,000,825 5/ 35 Davies 219-335 2,448,669 9/48 Green 219-335 2,470,972 5/49 Boger 219-205 X 2,860,226 11/58 Williams et al. 219-336 X FOREIGN PATENTS 410,169 5/ 34 Great Britain. 609,147 9/ 48 Great Britain.

RICHARD M. WOOD, Primary Examiner.

ANTHONY BARTIS, Examiner. 

